The present invention relates to a control unit usable in a color television receiver having a circuit for transmitting and receiving a remote control signal to control a signal processing circuit and a channel selection circuit.
In a recent color television receiver, a microcomputer or a digital signal processing circuit is used so that the television signal is processed or controlled by digital data. When the signal is processed in an digital form, it is necessary to store an initial data because necessary signals are detected from the normally operating color television receiver with reference to the initial data and the detected signals and the initial data are compared in a control microcomputer to assure that the color television is always operated correctly. One example is an automatic white balance adjustment. As automatic white balance adjusting means, a low voltage source and a high voltage source are provided for each of the red, green and blue colors. The reference primary color voltages from the low and high voltage sources are applied as inputs to a chrominance output circuit of the color television receiver to which all adjustments including the white balance have been completed. The beam currents are detected as voltages, which are converted to digital signals, which in turn are stored in a memory as the initial reference data. This is done for each of the red, green and blue colors. During the normal operation of the color television receiver, the low and high voltages for the respective colors are applied to the chrominance signal output circuit in a blanking period and the beam current for one of the primary colors is compared with the initial reference data to detect a deviation of the white balance, and based on the deviation, the DC level and the gain of the chrominance signal are controlled such that the beam currents for other primary colors match the stored three-primary color ratio. The present invention relates to means for adjusting such initial reference data.
On the other hand, in a color television receiver which uses a digital signal processing circuit, if the initial data need be modified because peripheral parts are replaced due to trouble in a completed television receiver, it is necessary to change the initial data in some manner. In the past, the necessary adjustment was done by using an adjusting jig.
The configuration of a conventional digital color television receiver is explained with reference to FIG. 1 in which numeral 1 denotes a control microcomputer, numeral 2 denotes control keys for turning on and off a power supply, selecting a channel and controlling the sound level, numeral 3 denotes a remote control transmitter, numeral 4 denotes a receiver circuit for receiving a remote control signal from the remote control transmitter, numeral 5 denotes a memory, numeral 6 denotes a channel selection circuit, numeral 7 denotes a tuner, numeral 8 denotes an intermediate frequency amplifier, numeral 9 denotes a digital signal processing circuit, numeral 10 denotes a chrominance signal output circuit, numeral 11 denotes a drive circuit, numeral 12 denotes a cathode ray tube, numeral 13 denotes an audio output circuit and numeral 14 denotes a sound output device.
The basic operation of FIG. 1 is explained below. The control microcomputer 1 discriminates the manipulation by the control keys 2 or the remote control transmitter 3 and controls the memory 5, the channel selection circuit 6 and the digital signal processing circuit 9. The channel selection data and the signal processing initial data have been stored in the memory 5, and they are read and written as required. The memory 5 may be a non-volatile memory such as an MNOS memory or a FAMOS memory, or a volatile memory backed up by a battery.
As the channel is selected by the control key 2 or the remote control transmitter 3, the control microcomputer 1 and the channel selection circuit 6 are operated to read out the channel selection data from the memory 5 and apply a tuning voltage corresponding to the channel selection data to the tuner 7. The television signal selected by the tuner 7 is converted to video/audio signal through the audio intermediate frequency amplifier/detector 8, and the signal is applied to the digital signal processing circuit 9. The digital signal processing circuit 9 converts the signal from the intermediate frequency amplifier/detector 8 to a digital signal by an analog/digital converter (not shown), processes the video/audio signal, controls various operations in accordance with instructions from the control microcomputer 1, then converts the signal to an analog signal by a digital/analog converter (not shown), and supplies a chrominance signal to the chrominance signal output circuit 10 through a line 16. The chrominance signal output circuit 10 adjusts the DC level and the gain of the chrominance signal by the digital data supplied from the control microcomputer 1 through a line 15. The digital data is converted to analog data by the digital/analog converter and the converted analog data is supplied to the chrominance signal output circuit 10. The chrominance signal adjusted by the chrominance signal output circuit 10 is applied to the drive circuit 11 which drives the CRT 12. On the other hand, the audio signal is applied to the audio output circuit 13 through a line 17 to drive the sound output device 14.
In the digital television receiver, almost all adjustments are done in accordance with the digital data from the control microcomputer 1 as explained above in connection with the operation of the chrominance signal output circuit 10. Accordingly, the externally adjustable parts such as volume controllers or trimmer capacitors used in the prior art analog television receiver tend to be eliminated.
In the adjustment of such digital television receiver, a special adjusting jig as shown in FIG. 2 has been used in the past. FIG. 2 illustrates an example of the adjusting method for the digital television receiver. The like numerals to those shown in FIG. 2 denote the blocks having the like functions. Only those blocks which are necessary for the explanation are extracted. In FIG. 2 numeral 18 denotes an adjusting jig and numeral 19 denotes a signal switch for a normal mode and an adjustment mode. The operation of the adjusting device is explained below.
In the normal mode, the signal switch 19 is connected to a terminal X, and a control line 20 for the memory 5 and a control line 21 for the digital signal processing circuit 9 and the chrominance signal output circuit 10 are connected to the control microcomputer 1. In the adjustment mode, the signal switch 19 is connected to a terminal Y. Thus, the control line 20 for the memory 5 and the control line 21 for the digital signal processing circuit 9 and the chrominance signal output circuit 10 are connected to the adjusting jig 18. In the adjustment mode, the adjusting jig 18 sends digital data to the digital signal processing circuit 9 and the chrominance signal output circuit 10 through the control line 21 to effect necessary adjustments. After the adjustment, the adjusting jig 18 writes the adjusted digital data into the memory 5 through the control line 20. In this manner, the adjustment is carried out.
In the above arrangement, a special adjusting jig is required for the adjustment. Even for a simple adjustment for the field replacement of a part, the control line must be switched and the adjusting jig must be provided. This is time consuming.